Review and Measurements of Okto DAC8 8Ch DAC & Amp

[gandalfandula]

I'm interested in this DAC and I think it works well for my multichannel active system, but I'm a bit perplexed by the Vrms output spec. It's given as 4.1V standard, but it can be modified by Okto. I'm thinking about rebuilding my system around this DAC, which will ultimately entail getting new amps.

I may want different amps for different drivers and I'm afraid this would create a mismatch in the input sensitivity. I could attenuate the output in the Okto, but doesn't this mean I would sacrifice total headroom? For example if I kept the Okto at 4.1V, and I had a woofer amp with a 4V input sensitivity, but a high frequency amp with a 2V input sensitivity, I couldn't drive the woofer amp fully without clipping the high frequency amp - or do I have that wrong? I'd need to attenuate the woofer amp output. How have others planned around this? Is it better to go with a lower output V for this reason? Some professional gear (e.g. Benchmark AHB2 that I've been looking at) can vary the input sensitivity but this is not very common in consumer equipment that I've seen.

 

[mdsimon2]

For example if I kept the Okto at 4.1V, and I had a woofer amp with a 4V input sensitivity, but a high frequency amp with a 2V input sensitivity, I couldn't drive the woofer amp fully without clipping the high frequency amp - or do I have that wrong? I'd need to attenuate the woofer amp output.

I answered your PM about this but I think you raised some points here that are a bit different and worth discussing.

First, depending on your speakers it is highly likely that even if you have the same input sensitivity amplifiers for high and low frequencies you will want to attenuate the high frequencies as in general high frequency drivers are more sensitive. So adding 6 dB of attenuation to the high frequency amp output (either in the Okto itself or in a separate DSP) so that the amplifiers clip at the same volume position is likely not a big deal.

Second, even if you did not want to attenuate high frequencies compared to low frequencies musical content in general has lower levels at higher frequencies so it is very unlikely that your high frequency amp will be driven in to clipping.

In general I think ~4 V is a good output voltage for most cases as it gives the flexibility to drive pretty much any consumer amplifier to clipping and have a bit of headroom to compensate for lower level recordings.

Michael

 

[manisandher]

I can't get my dac8 PRO to output the first two USB channels on its AES output. Does anyone know if the dac8 PRO can be used as a USB-to-AES converter?

 

[Zooqu1ko]

I can't get my dac8 PRO to output the first two USB channels on its AES output. Does anyone know if the dac8 PRO can be used as a USB-to-AES converter?

I have stumbled upon the same problem almost exactly a year ago. Here's what Pavel has responded:

I am sorry for my late reply. We have ran some tests and it seems like some dac8 PRO's firmware versions have a bug that prevents the AES/EBU from correct operation. It is, in fact, transmitting zero or silence all the time, which is why you have seen a seemingly valid signal on the oscilloscope.

My apologies for the inconvenience, we will fix that in the future firmware version and attempt to release an update for the existing units.

Still waiting for a firmware update. In the meantime, I've bought one of those, and it's working flawlessly for my purposes. Since I only needed something that outputs AES from USB, I could have gotten away much cheaper with any other XMOS -> S/PDIF device and one of the Canare BPJ-XP-TRB that I already own. All that obviously won't work if you need that output to be synchronized with the DAC8.

 

[manisandher]

Thanks, that's great information. So, in principle it's possible, but requires a firmware update from Okto. I'll send them an email, but won't hold my breath for a reply. Such a shame, as I really like what Okto have done with the dac8.

 

[Zooqu1ko]

Thanks, that's great information. So, in principle it's possible, but requires a firmware update from Okto.

I believe a downgrade would work as well, but I'm not sure what version would be that last that worked.

 

[Torbachkristensen]

I got an email with firmware and update instructions - will ask if I can share here

 

[manisandher]

I got an email with firmware and update instructions - will ask if I can share here

It would be awesome if you could .

Mani.

 

[sumitc]

I got an email with firmware and update instructions - will ask if I can share here

What issue were you having that this version addresses? I have been having pops and crackles with high sample rate recordings and it will be great it that issue is addressed here.

 

[Kal Rubinson]

Perhaps it would be useful for all of us to cite the firmware version we are using when commenting on problems/needs.
For example, I am on v1.3 and I am not aware of any issues so far.

 

[sumitc]

Perhaps it would be useful for all of us to cite the firmware version we are using when commenting on problems/needs.
For example, I am on v1.3 and I am not aware of any issues so far.

I'm on ver 1.42.

 

[Feyire]

I got an email with firmware and update instructions - will ask if I can share here

You're on version 1.00 right? Please let me know how it goes, because I'm also on version 1.00, as I have one of the very first few produced DAC8 Stereos.

 

[manisandher]

My dac8 PRO came with version 1.42 installed, and I haven't changed it. (What's the latest version, does anybody know?)

It's worked flawlessly since I received it well over a year ago now. Up until recently, I'd never touched its AES inputs/outputs. It seems its AES output doesn't work correctly, but I think I need to look into this a bit further.

Fortunately, it's no big deal for how I use it, but it'd be nice to know that everything's working as it should.

I still think the dac8 PRO is a phenomenal piece of kit!

 

[dualazmak]

My DAC8PRO arrived on May 19, 2020. Firmware version 1.32, the apple remote also arrived together with DA8PRO.
USB driver version is DIYINHK_UsbAudio_v4.59.0_2019-02-28.
I never used AES/EBU In, but AES/EBU digital Out (through digital out of CH1+CH2) is working perfectly (please refer to my post here), even though not in daily use at present.
I operate DAC8PRO in pure USB mode receiving 8 channels from DSP(XO/EQ, delay) EKIO via ASIO driver DIYINHK_UsbAudio_v4.59.0; of course through single USB 2.0 cable.

You can find my latest system setup as of May 30 2022 here.

So far, no issue/trouble at all, really amazing 8-Ch DAC!!

 

[gandalfandula]

I answered your PM about this but I think you raised some points here that are a bit different and worth discussing.

First, depending on your speakers it is highly likely that even if you have the same input sensitivity amplifiers for high and low frequencies you will want to attenuate the high frequencies as in general high frequency drivers are more sensitive. So adding 6 dB of attenuation to the high frequency amp output (either in the Okto itself or in a separate DSP) so that the amplifiers clip at the same volume position is likely not a big deal.

Second, even if you did not want to attenuate high frequencies compared to low frequencies musical content in general has lower levels at higher frequencies so it is very unlikely that your high frequency amp will be driven in to clipping.

In general I think ~4 V is a good output voltage for most cases as it gives the flexibility to drive pretty much any consumer amplifier to clipping and have a bit of headroom to compensate for lower level recordings.

Michael

Thanks Michael, this is some good perspective.

In other news: the ordering opened up again so I pulled the trigger on this one. I actually got a personal message on my order status 7 minutes after purchasing which said it would be shipped within 2 weeks! Perhaps their customer service is improving?

 

[dartinbout]

Wow! Since following this gift from the gods, I've only seen this open for orders 2-3 times. You can even order it any color you like (as long as it's silver). I have it on good authority the silver clears more veils! Seriously this is an amazing bit of kit.

 

[Deribas]

I am glad someone brought up a noise issue recently. My enjoyment of music played through Okto DAC8 pro (FW 1.42 from factory) is rather limited by transient, nearly predictable noise that I cannot get rid of. Please let me know if the following issues resembles something that someone else has experienced, or better yet, solved:

I play mostly multichannel hi-res FLAC and DSD files (as DOP64) on a Mac Mini running JRiver 29, connected to Okto DAC via pure USB connection. With multichannel DSD files (stored as .iso SACD rips), I am bitstreaming as DOP64, which is the only DSD format that seems possible to use with Mac OS and this DAC. When playing the first DSD track after turning the system on, usually within the first minute of playback, but not right at the beginning, I get a horrible “white” (or pink?) noise over the music that lasts for a few seconds and then fades away. Then the DSD album would play without issues for the remainder of the listening session. Next day, with the different SACD-sourced DSD album, the problem recurs. I do not use a room-correction software while I am trying to solve the noise issue, though in the future I would like to go back to using Dirac Live.

I am grateful for any validating observations and any potential solutions, whether some critical settings in Jriver or the Okto DAC Pro itself. BTW, if the DSD files are converted into hi-res FLAC in Jriver itself before playback, I do not believe the noise occurs.

 

[Kal Rubinson]

I play mostly multichannel hi-res FLAC and DSD files (as DOP64) on a Mac Mini running JRiver 29, connected to Okto DAC via pure USB connection. With multichannel DSD files (stored as .iso SACD rips), I am bitstreaming as DOP64, which is the only DSD format that seems possible to use with Mac OS and this DAC.

My situation is different in that I use a Mac Mini Win-based PC running JRiver 29, connected to Okto DAC via pure USB connection. With multichannel DSD files (stored as .iso or .dsf from SACD rips), I am bitstreaming as native DSF DOP64, which is the only DSD format that I need seems possible to use with Mac OS and this DAC. No noise problems.

Using DoP also doubles the required transmission banwidth.

FWIW.

 

[gandalfandula]

Regarding the Okto's AES/EBU inputs: I have no devices that natively output that format. But from what I have read I think I can convert BNC coax to AES/EBU using an impedance transformer like this:

Neutrik NADITBNC-M - AES/EBU Impedance Transformer

Buy Neutrik NADITBNC-M - AES/EBU Impedance Transformer featuring Inputs 75 Ohm BNC, Outputs 110 Ohm XLR, Matches Balanced to Coaxial Lines, Allows Long Cable Runs for Digital Audio, Simple to Use, Passive Unit, Cost-Effective Impedance Matching. Review Neutrik null

www.bhphotovideo.com

I'm looking to go:

Allo digione signature player > BNC > impedance transformer to AES/EBU > Okto 2 ch input > out USB (to another Rpi running Camilladsp) > back into Okto via USB > out to amps

I've also got at least one Toslink source. I have a cheap Toslink to coax adapter that outputs RCA terminated coax: is there any reason this wouldn't work with the impedance transformer as well?

 

[Open Mind Audio]

My situation is different in that I use a Mac Mini Win-based PC running JRiver 29, connected to Okto DAC via pure USB connection. With multichannel DSD files (stored as .iso or .dsf from SACD rips), I am bitstreaming as native DSF DOP64, which is the only DSD format that I need seems possible to use with Mac OS and this DAC. No noise problems.

Using DoP also doubles the required transmission banwidth.

FWIW.

Same here but the PC running JRiver connects to my Oppo UDP-205 via ethernet on my home network. Otherwise all the same running multichannel DSD stored as native DSF. No noise problems - works tremendously. Only complaint is that I prefer the user experience of Roon over JRiver, but my present set-up won't allow Roon multi-channel, so I stick with JRiver for multi and Roon for most stereo.